This invention relates to filter systems and methods for cleaning liquids by removing unwanted contaminants and particulates from liquids and to systems and methods for cleaning unwanted contaminants and particulates from the filter elements employed in such filter systems.
In the past filter systems for cleaning liquids equipped with filter systems for removing contaminants and particulates have periodically cleaned the filter elements by using mechanical contact devices in the form of scrubbing, scraping or brushing particulates from the surfaces of the filter elements. The mechanical contact method can damage the face of the filter elements leading to their early failure with the result of requiring early replacement thereof. Moreover excessive amounts of contaminants and particulates have reached the filter elements, thereby requiring more frequent cleaning of the filter elements and concomitantly reducing the efficiency of the filter systems.
Accordingly it is an object of this invention to provide apparatus and a method for cleaning such filter elements without damaging the filter elements by mechanical contact with the filter elements.
Another object of this invention is to reduce the amount of particulate material which reaches the filter elements.
In accordance with this invention, a vessel comprises a vessel which is a vertically oriented container. A swirl plate spirals around on the inner wall surface of the vessel. A nozzle injects unclean liquid onto the lower surface of the swirl plate so that the swirl plate deflects the unclean liquid down towards the bottom of the vessel generating a liquid vortex flowing causing particulates to precipitate towards the bottom of the vessel. Above the swirl plate, a generally cylindrical filter collects particles on its exterior surface. In a filter element cleaning cycle, the filter element rotates on a shaft and is cleaned periodically by high pressure sprays of clean process liquid from nozzles juxtaposed with the filter; and the particulates are flushed from the vessel.
The downwardly sloped swirl plate affixed to the inner surface of the vessel is provided to direct the liquid downwardly thereby generating a liquid vortex in the lower portion of the vessel. The vortex is created as a liquid is ejected from the inlet nozzle directed thereby tangentially to the vessel wall at a relatively high velocity. The liquid vortex separates some suspended contaminants and particulates from the liquid before it flows upwardly and passes through a filter. In particular, the swirl plate in the vessel induces the vortex, which creates a centrifugal force causing the heavier particulates to migrate outwardly onto the inner surface of the wall of the vessel. Simultaneously the vortex forces all of the liquid to flow downwardly initially, away from the filter element as the liquid carries all of the heavier particulates downwardly therewith. as a result, the heavier particulates settle out at the bottom of the vessel. As the liquid reaches the bottom of the vessel it reverses direction and flows upwardly in a central column within the vortex, thus allowing cleaner liquid to flow through the central column, within the center of the vortex, towards the filter element located closer to the top of the vessel. However, the particulates remaining suspended within the liquid flows upwardly towards the filter element. As liquid flows though the filter element, it removes additional particulates therefrom during the filtering operation of the filtering system of this invention.
The filter element is adapted to be rotated by a motorized filter assembly which is mounted by flanges to the upper portion of the vessel. During the periodic filter cleaning operation of the system of this invention, the filter element is cleaned by removing particulates therefrom. An array of high pressure spray cleaning nozzles juxtaposed with the filter element direct a plurality of flat sprays of process liquid tangentially to the surface of the rotating filter, which efficiently cleans the outer surface of the filter element.
Removing the particulates from the exterior of the filter element restores the filter element to a clean condition, thus allowing the filter element to remain in operation for longer durations and thereby extending the life of the filter element, while flushing of particulates to the bottom of the vessel where they are collected until such time as they are removed from the vessel through a drain at the bottom thereof.